This invention relates to a hybrid catheter guide wire apparatus with improved torque and flexure characteristics.
Catheter guide wires have been used for many years to xe2x80x9cleadxe2x80x9d or xe2x80x9cguidexe2x80x9d catheters to desired target locations in the human body""s vasculature. The typical guide wire is from about 135 centimeters to 195 centimeters in length, and is made from two primary piecesxe2x80x94a stainless steel core wire, and a platinum alloy coil spring. The core wire is tapered on the distal end to increase its flexibility. The coil spring is typically soldered to the core wire at a point where the inside diameter of the coil spring matches the outside diameter of the core wire. Platinum is selected for the coil spring because it provides radiopacity for X-ray viewing during navigation of the guide wire in the body, and it is biocompatible. The coil spring also provides softness for the tip of the guide wire to reduce the likelihood of puncture of the anatomy.
Navigation through the anatomy is achieved by viewing the guide wire in the body using X-ray fluoroscopy. The guide wire is inserted into a catheter so the guide wire protrudes out the end, and then the wire and catheter are inserted into a vessel or duct and moved therethrough until the guide wire tip reaches a desired vessel or duct branch. The proximal end of the guide wire is then rotated or torqued to point the curved tip into the desired branch and then advanced further. The catheter is advanced over the guide wire to follow or track the wire to the desired location, and provide additional support for the wire. Once the catheter is in place, the guide wire may be withdrawn, depending upon the therapy to be performed. Oftentimes, such as in the case of balloon angioplasty, the guide wire is left in place during the procedure and will be used to exchange catheters.
As the guide wire is advanced into the anatomy, internal resistance from the typically numerous turns, and surface contact, decreases the ability to advance the guide wire further. This, in turn, may lead to a more difficult and prolonged procedure, or, more seriously, failure to access the desired anatomy and thus a failed procedure. A guide wire with both flexibility and good torque characteristics (torsional stiffness) would, of course, help overcome problems created by the internal resistance.
Among the approaches suggested in the prior art for increasing the flexibility of the tip of a guide wire is that of cutting axially spaced grooves in and near the tip, with the depths of the grooves increasing toward the tip. See U.S. Pat. No. 5,437,288. The use of cuts to increase flexibility on one side only of a tubular guide wire is disclosed in U.S. Pat. No. 5,411,483.
It is an object of the invention to provide an improved catheter guide wire apparatus.
It is also an object of the invention to provide such apparatus which exhibits both torsional stiffness, bending flexibility, and longitudinal strength.
It is a further object of the invention to provide such apparatus which is simple in design and construction.
It is another object of the invention, in accordance with one aspect thereof, to provide a catheter guide wire apparatus with improved flow directability characteristics.
The above and other objects of the invention are realized in a specific illustrative embodiment of a hybrid catheter guide wire apparatus formed of a thin elongate solid body of material which tapers or is otherwise reduced in diameter to a thinner distal termination, and a thin elongate tubular body of material disposed co-linearly to the distal end of the solid body to circumscribe at least a portion thereof. The tubular body, which is constructed to have greater lateral flexibility than the solid body, while retaining torsional stiffness, is attached at its proximal end to the solid body, or at its distal end to the solid body, or at both ends to the solid body. Cuts may be formed in the tubular body, transversely thereof to give the guide wire flexibility without significantly reducing torsional stiffness or strength.